Plant organs form post-embryonically from the meristems, structures in which cell division and cell specification are closely integrated. In the floral meristem, three classes of homeotic genes interact to specify sepals,petals, stamens and carpels. On p. 3147, Wang and Chen report that HUA ENHANCER3 (HEN3) acts in the pathway of AGAMOUS, an Arabidopsis homeotic gene required for stamen and carpel specification. By analysing hen3 mutants, the researchers found that HEN3, which was isolated as an enhancer of the hua1 hua2 double mutant phenotype, is required for cell-fate specification in floral meristems and cell expansion in leaves. They also show that HEN3 is the homologue of mammalian cyclin-dependent protein kinase 8 (CDK8), which is known to be required for cell differentiation in yeast and Dictyostelium. However, this is the first demonstration that CDK8 has a developmental function in a higher eukaryote.

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